1. Field of the Invention
The present invention relates generally to a low power video compression system and, more particularly, to a video compression system that combines optical, electronic analog, and digital technologies to optimize its power consumption characteristics.
2. Background of the Related Art
Miniaturization of electronic system components has been a goal of designers since the dawn of electronics. The driving force behind the move to miniaturize electronic components primarily stems from the need to make the products in which they are used more portable. Commercial products that have made great strides in this area include, for example, portable laptops and CD-players.
An area where miniaturization is playing a major role is in the design of micro air vehicles (“MAV”). MAV's are airborne vehicles that are no larger than 15 centimeters (six inches) in length, width or height and perform a useful military mission at an affordable cost. The military envisions that individual soldiers at the platoon level or below will use such vehicles for reconnaissance and surveillance, battle damage assessment, targeting, emplacing sensors, communications relays, or for sensing chemical, nuclear, or biological substances. Commercial applications also exist including traffic monitoring, border surveillance, fire and rescue operations, forestry, wildlife surveys power-line inspections, and real-estate aerial photography. The vehicles will have to be able to conduct real-time imaging, have ranges up to 10 kilometers and speed of up to 30 miles per hour for missions that are 20 minutes to two hours long.
A MAV prototype was test flown on August 2000. The “Black Widow” MAV (AeroVironment, Inc., Simi Valley, Calif.) had an endurance of 30 min., maximum range of 1.8 km, and a mass of 80 g. Through an extensive evaluation, it was determined that the combination of a battery as an energy source and motor driven propeller provided the best propulsion system. A large portion of the MAV's mass is due to the mass of the battery. Therefore, any improvement that reduces the need for battery power will improve the performance by allowing the battery to be reduced in size, resulting in a lighter aircraft, or allowing the battery to remain the same size, resulting in more power for increasing endurance.
The Black Widow MAV included a video payload including a custom color CMOS camera and a custom video transmitter. The color CMOS video camera had a mass of 1.7 g, utilized 150 mW of power, and had a resolution of 510.times.488 pixels. The video transmitter had a mass of 1.4 g, power input of 550 mW, and power output of 100. To get the video from onboard to the ground a radio frequency (RF) transmitter operating at 2.4 GHz was used. The transmitter takes the analog video stream as an input, modulates it using frequency modulation (FM), and outputs it as a RF signal. A detailed discussion of the Black Widow MAV can be found in “Development of the Black Widow Micro Air Vehicle” by Joel M. Grasmeyer and Matthew T. Keennon of AeroVironment, Inc., American Institute of Aeronautics and Astronautics, Paper Number AIAA-2001-0127.
There are number of disadvantages associated with present video systems intended for use in highly portable equipment such as the Black Widow MAV including relatively high power consumption, high noise, and low range.